Auxiliary case shift mechanism for teletypewriter receivers to prevent garble



J1me 1965 R. J. RAMIG, JR 3,190,428

M FOR TELETYPEWRITE AUXILIARY CASE SHIFT MEGHANIS RECEIVERS TO PREVENT GARBLE Filed Aug. 24, 1962 INVENTOR ROBERT J. RAMIG JR.

ATTORNEY each intelligence bearing pulse.

United States Patent snaaazs AUXELEARY (CASE SHEET MECHANISM FOR TELETYFEWRETER RECEEVERS T0 ?REVENT GARBLE Robert J. Ramig, J12, Niles, lllL, assignor to Teletype Corporation, Slrolrie, Ill, a corporation of Delaware Filed Aug. 24, 1962, er. No. 219,2tl8 6 Claims. (63. 197-71) This invention pertains to improvements in teletypewriters and more particularly to a manually controllable case shaft mechanism for teletypewriters which will shift the printing mechanism from either one of two possible printing conditions to the other.

In most teletypewriter machines two primary functions are performed, that of transmitting permutation code signals from one machine to another and receiving such signals and converting them to mechanical motions to provide printed intelligence. Accordingly, this type of teletypewriter machine has both a receiving section for printing the received message and a transmitting section to control the transmission of signals over a signal line to other receiving machines. A keyboard for controlling the generation of code signals representative of functions of character symbols is provided in the transmitting section of the teletypewriter.

Among the function keys on the keyboard are a figures shift key and a letters shift key. These keys when operated will cause, through the generation of appropriate signals, the printing mechanism of any teletypewriter controlled by the signals to shift to the upper case or lower case position, respectively. In addition to shifting the printing mechanism on the teletypewriter machine ininitiating the function, the code representing the particular shift function will be transmitted over the signal lines and correspondingly effect a similar change at all teletypewriter machines receiving the code.

Since these functions are transmissible as permutation code signals over the signal line they are subject to the various types of interference to which all transmitted teletypewriter signals are subject, including extraneous line noise which is interpreted, in some instances, by the teletypewriter machine, as a part of the transmitted code combination, or distortion in the configuration of When the above-mentioned interferences appear on the signal line they may cause errors in the transmission of the code. A common error is the unintended shifting from the figures to the letters position due to the peculiarity of a widely used permutational code, in which the lower case shift in represented by the all-marking condition, and a large burst of noise on the line may simulate this condition. Similarly the figures or letters code signals may not actuate those functions at the distant station due to an excessive amount of distortion appearing on the intelligence bearing pulses comprising a permutational code representing either of those functions. When this occurs the receiving machine at a distant point may continue to print in the case shift condition in which it had been printing, when in fact the printer should be printing in the opposite conditon. Thus, the receiving macihne which has not been placed in the right case shift condition may print the letters transmitted as figures and the figures as letters, resulting in what is termed garble. Garble may also occur when the operator inadvertently fails to transmit a carriage shift signal, figures or letters, although the message he is transmitting requires such a shift.

a code signal which will combine with the incoming code signal to produce an unpredictable resultant signal. Receiving only teletypewriter machines which do not have transmitting capabilities are limited to the functions'which are received by them and if a figures or letters code is misinterpreted or is not properly received, the teletypewriter machine will continue to print in the former case shift condition which will result, as in the case of the transmitting-receiving teletypewriters, in garble. At present an operator at a receiving only teletypewriter machine can in no prescribed manner cause a case shift of the teletypewriter machine.

Accordingly, it is an object of this invention to enable a teletypewriter printing mechanism to be shifted from either of two possible case shift conditions to the other by a manually operable control located on that machine.

Another object of the invention is to enable a case shift in a teletypewriter printing mechanism independently of the receiving selector mechanism of that teletypewriter.

Still another object of the invention is to enable a case shift in the teletypewriters printing mechanism from either of two possible operating positions to the other while the teletypewriter is receiving a message.

A feature of the present invention is a manually controllable mechanism to move the case shift code bar, which effects a case shift in the printing mechanism, from either one of two possible positions to the other.

Another feature of the invention is the utilization of a truncated triangular recessed channel cam moving at a relatively fast rate of speed to urge a follower, attached to the case shift code bar, in one of two transverse rectilinear directions to effect a case shift in the printing mechanism of a teletypewriter.

In accordance with the present invention a manually controllable cam assembly, independent of the normal code responsive case shift selection means, is employed to actuate the letters-figures case shifting means in a teletypewriter machine, thereby to change the position of the printing assembly to effect the proper case positioning of the teletypewriter. The shifting is accomplished by means of a lettersfigures shift bar which is urged in one of two recetilinear directions by a truncated triangularly shaped channel cam in which a follower pin, attached to one end of the shift bar, is guided.

The cam, in the preferred embodiment, is actuated by a solenoid which may be momentarily energized by de pressing a key switch on the front panel of the associated teletypewriter. A force perpendicular to the rectilinear motion required to effect a letters-figures shift is imparted to the cam assembly, hence, the cam urges the follower to transverse a rectilinear path distance by urging the follower along the inner peripheral edge of the truncated triangularly shaped cam to its truncated vertex where the momentum imparted to the letters-figures code bar carries the follower pin to alignment with the opposite leg of the triangular channel cam whereupon release of the cam assembly, due to de-energization of the solenoid, permits a spring urged means to restore the cam assembly to its initial position, thereby guiding the cam follower to the opposite base angle of the channel cam, effecting a longitudinal displacement of the cam follower which provides a carriage shift from one of two possible conditions to the other.

Other objects and features of the invention will become apparent from the following detailed description when read in conjunction with the following drawings in which:

FIG. 1 is a fragmentary front elevationed view of a typical letters-figures case shifting mechanism for a teletypewriter machine;

' scale taken substantially along the FIG. 2 is a fragmentary view taken substantially along the line 2.-2 of-FIG. 1 in the direction of the arrows;

FIG. 3 is a fragmentary sectioned View, on an enlarged line 33 of FIG. 2 in the direction of the arrows; and

FIGS. 4, Sand 6 are fragmentary views, on an enlarged scale, of the lower portion of FIG; 2 showing the positions taken by the parts in carrying out the case shiftoperation. The preferred embodiment of the invention as shown in the drawings is designed to operate in conjunction with the printing'telegraph page-printer disclosed in US. Patent 2,658,105 granted on November 3,1953 to closure of the above named patent and the present invention have been given thesame reference numerals.

In the aforementioned patent. to B. 'F. Madsen the case cross piece 19 on the plunger 33 to limit the extent of movement of the plunger 33 and cam assembly 34 downwardly under the influence of the spring 16.

shift selection is made under control of received signals by spectively, in the slide 75. The shift slide 75 carries av pair of studs. 82 and 83 that co-operate with a pair of shift link breaker slides 84'and 85 to selectively position them for actuation by a vertically 'recipr'ocatable main bail 86. The bail 86 carries a'pair of breaker slide bails94and 95 that are pivotally mounted on the bail 6 and selectively actuate theslides 84 and 35, respectively, .to selectively collapse or break toggles or knee actions 109 or 111, re-

spectively, that are interconnected with a plate 116. The operation of the knee actions 109-and111 selectively positions a channel member 118 which controls the case con' dition of the apparatus. All of the mechanism described thus far, and its operation are clearly described in detail inthe aforementioned patent to B. F. Madsen.

. The internal cam 31 is in the form of a truncated isosceles triangle and the normal resting position of the cam follower pin is in'oneor the other of the base angles 44 and 45 of the channel. If the-pin 30' is in the position shown in FIGS. 2 and 4, (upwardly as shown in the drawing) the perpendicular motion of the internal cam assembly 34 will cause the cam follower pin 30 to be urged along one leg 35 (FIG. 4) of the internal cam 31.

This results'in rectilinearmovement to. the left of code bar 72. The sudden acceleration of the plunger. 33 toward the body of the solenoid 32, upon energization'thereof, imparts sufficient momentum to cam follower 3th to carry the cam follower 30 across, the vertex 36 of the channel 31 so that, upon the release of the plunger '33 by the solenoid 32, the cam follower pin 30 is urged along the other leg 47 of the internal channel by the triangular cam guide, 46, to a resting position in the other base angle 44"of the channel. This will cause the letters-figures shift code bar 72 totraverse the distance itwould normally traverse upon reception 'by'the teletypewriter machine Qof the appropriate permutational function code. However, in this instance, the transverserectilinear motion is imparted to the. letters-figures shift bar 72 inde- To produce the transverse rectilinear motion in the letters-figures shift codebar 72 independentlyof the receiving selector mechanism, regardless of the code being I end of the extension 29'is securely fastenedto the code bar 72 while theother end has fixed thereon a cam follower pin 30. This cam follower pin 34) is disposed in a pendently of the receiving selector mechanism.

Assume now that the teletypewriter letters-figures shift mechanism, and particularly the channel member 118, is in the position shown in FIG. 1, which places the cam follower pin 30in the base angle 45 as shown in FIGS. 2 and 4. This is the letters or lower case condition of the teletypewriter. If the operator of the teletypewriter observes that the teletypewriter is recording unintelligible'copy, or for any other reaso n concludes that the machine should be placed in the figures or upper case condition, he manually depresses and then releases a switch button (not shown) located on the keyboard of the teletypewriter machine for completing an energizing circuit for solenoid 32.

The solenoid will become energized, attracting plunger 33 toward the body of the solenoid 32. 'During this operation the main bail 86 is reciprocating at a fixed rate of speed as determinedby the associated mechanism of the teletypewriter machine thereby allowing the case shift bar 72 "to traverse the appro'rpiate distance toeffect a case shift. As the plunger 33 of solenoid 32 is attracted toward the body of the solenoid and carries with it the cam assembly 34, the cam follower pin 30 will be urged in a truncated triangularly shaped channel 31 which forms'aninternal cam, guide for thefcam follower pin 30 for actuating'the code bar 72 when a channel cam assembly 34 is moved ina direction perpendicular to' the rectilinear motion required to shift the figures-letters code bar 72.

The preferred form of activating means for the cam assembly 34 comprises solenoid 32 but any other suitable the desired direction, When the solenoid 32 is energized, a plunger 33 is attracted to the body of the solenoid 32 thereby urgingthe cam assembly 34 in a direction perpendicular to the rectilinear transverse motion necessary to effect a shift in the carriage mechanism via the 'lettersfigures shift code bar extension 29 and codebar 72.

The cam assembly 34 is attached to the plunger 33 and is guided for rectilinear movement by a fixed stud 12 which is mounted on a portion 13 of the frameof'the'machine.

The stud 12 has a reduced shank 14 which is straddled 16 has oneof its ends attached to the plunger 33 and its ,otherend fixed to a bracket 17 which is mounted on the casing of the solenoid 32. The bracket 17 also has fixed to it'a stop member 18 which extends into the path of a mechanism may be used to move the cam assembly 34 in 7 rectilinear direction, according to'the slope of the righthand leg 35 ;of the channel.

Manifestly, the carnfollower pin 30 can move only rectilinearly, namely, parallel to the base of the triangular channel 31 as shown in FIGS. 4, *5 and 6. Itwill be noted that the cam'follower pin 30jmoves only in a straight line, represented by the dotted line '39, throughout the transversely directed shifting motion imparted to the cam asinto interfacial relationship with the solenoid body 32, the

cam assembly 34 suddenly comes to rest, where the follower pin 30 will-be held due to the ball detent arrangement 37 associated with the bar 72. The cam follower pin 31), however, is free to continue its transverserectilinear motion'as there has been aquantity of kinetic energy, in the form of rectilinear inertia imparted to the code shift f bar 72 and hence to cam follower pin 30; This inertia will urge thev cam follower pin 30; across the truncated portion 38 of the internal triangular channel 31 to the position 7 shown in solid lines in Upon release of the switch button, the operation of which need be only momentary, but which may be of any duration, the solenoid is released and spring 16 urges the cam assembly 34 back to its original or unoperated position, the cam follower pin 39 will then be forced to traverse the other leg 47 of the cam channel 31, at the entrance of which it had been presented by the operation of the magnet. When the cam assembly 34 comes to rest in its normal position the cam follower pin 30 will be the base angle 44 as shown in FIG. 6, thereby effecting a shift in the case shift selection mechanism without the use of the permutational code responsive selector mechanism.

It will be observed that the base portion 48 of the triangular channel permits transverse rectilinear movement of the cam follower pin 39 back and forth when the teletypewriter machine responds to an appropriate function code and imparts direct transverse rectilinear motion to the shift code bar 72. Thus, the cam follower 39 which is carried by the extension 29 of shift code bar 72 cooperates with the two sides of the triangular channel to be transferred by them from either end of the base of the channel to the other.

Manifestly, the change in transverse position of the letters-figures shift code bar 72 will cause the shift link breaker slides 84 and 85 and associated apparatus to function as hereinbefore described in changing the case position of the teletypewriter machine from the letters position to the figures postion. The cam assembly 34- will effect a change in the shift from the figures or upper case to letters or lower case in a manner similar to that described in a letters to figures except that the cam follower pin 30 will be urged in the right-hand transverse direction along the outside wall of triangular cam guide 46 of the channel 31 and subsequently by the right-hand wall of the internal triangular isosceles cam guide 46 but the end effect will be to traverse the distances between the left-hand 44 and right-hand 45 base angles of the truncated triangular internal channel 31 thus effecting a shift from letters to figures which is independent of the selector mechanism and code responsive means associated with the teletypewriter.

While there has been described and illustrated herein one of the known embodiments of this invention, it will be understood that the invention is not limited to the specific embodiment shown and described, but is capable of modification and rearrangement and substitution of components and elements without departing from the spirit of the invention.

What is claimed is:

1. In a case shift mechanism for a teletypewriter, a case shift code bar positionable to one or the other of two operating positions, means responsive to predetermined tele graph code signals to move said code bar to one or the other of said operating positions, a second and separate means for moving the case shift code bar, which means is independent of the signal responsive means and comprises sive to predetermined telegraph code signals to move said code bar to one or the other of said operating positions, a cam follower pin carried by said code bar, a cam memher having a depression of generally triangular contour, a triangularly shaped raised member centrally disposed in said depression and forming therewith a cam channel receiving and retaining said cam follower pin and affording by means of one of the sides of said triangular channel a path for movement of said cam follower pin during movement of said code bar by the signal responsive means, and means operable to move said cam member in a direction perpendicular to said rectilinear path of said code bar to effectively position said code bar to one or the other of two operating positions independently of the si nal responsive means.

3. In a case shift mechanism for a teletypewriter, a case shift code bar positionable to one or the other of two rectilinearly displaced operating positions, means responsive to predetermined telegraph code signals to move said code bar to one or the other of said operating positions, a cam follower member carried by said code bar, a cam assembly having a cam channel forming a continuous path in which said cam follower member is retained and affording in one portion of said channel a path for free movement of said cam follower member upon movement of said code bar by said signal responsive means and affording in the remaining portion of said channel a driving means for driving said cam follower member from either of two positions to the other, and means for operating said cam assembly to drive said cam follower member and code bar independently of said signal responsive means.

4. Apparatus as defined in claim 3 wherein said cam follower member statically assume-s one or the other of two positions in said cam channel.

5. :In a case shift mechanism for a teletypewriter, a case shift means positionable in one or the other of two positions, means responsiv to selected permutation code combination signals receivable by said teletypewriter to present said case shift means in one or the other of two possible positions, and a second and separate means operable independently of said ignal responsive means to move said case shift means from either one of its two possible positions, to which the signal responsive means had moved it, to the opposite one of its positions, said second and separate means including a member movable through a single cycle of reciprocation to move said case shift means to either of its two possible positions.

6. In a case shift mechanism for a teletypewriter, a case shift means positionable in one or the other of two positions, means responsive to permutation code signals received by said teletypewriter to present said case shift means in one or the other of its two possible positions, and a second and separate means independent of the signal responsive means to move said case shift means, when in either one of its two possible positions, to the other of its possible positions to compensate for a malfunction of the signal responsive means, said second and separate means including a camming member operative through a cycle of reciprocation to move said case shift means from either one of its two positions to the other one of its two positions, means biasing said camming member to a position to release said case shift means for control by the signal responsive means, and means for moving said camming member in one direction against the action of the biasing means to effect a portion of the cycle of reciprocation of it, said biasing means, in moving the camming member being effective to complete the cycle of reciprocation of it.

References Cited by the Examiner UNITED STATES PATENTS 2,049,468 8/ 36 Nichols 197-71 2,292,728 8 /42 Walti 745 67 2,339,785 1/44 Lake l97-71 2,452,372 10/48 Harkness 74-5 67 2,658,105 1 1/53 Madsen 178-25 3, 124,6 46 3 /64 Baum gartner 178-25 ROBERT E. PU-L'FREY, Primary Examiner.

EUGENE R. CAPOZIO, Examiner. 

1. IN A CASE SHIFT MECHANISM FOR A TELETYPEWRITER, A CASE SHIFT CODE BAR POSITIONABLE TO ONE OR THE OTHER OF TWO OPERATING POSITIONS, MEANS RESPONSIVE TO PREDETERMINED TELEGRAPH CODE SIGNALS TO MOVE SAID CODE BAR TO ONE OR THE OTHER OF SAID OPERATING POSITIONS, A SECOND AND SEPARATE MEANS FOR MOVING THE CASE SHIFT CODE BAR, WHICH MEANS IS INDEPENDENT OF THE SIGNAL RESPONSIVE MEANS AND COMPRISES A CAM FOLLOWER MEMBER CARRIED BY SAID CODE BAR, A CAM ASSEMBLY CONTAINING A TRIANGULAR CAM CHANNEL IN WHICH SAID CAM FOLLOWER MEMBER IS DISPOSED AND RETAINED, AND MEANS FOR OPERATING SAID CAM ASSEMBLY TO DRIVE SAID FOLLOWER MEMBER AND IMPART MOMENTUM TO SAID CODE BAR FOR EITHER ONE OF SAID OPERATING POSITIONS TO THE OTHER. 